One in five Macs has malware–but read the fine print

Sophos claimed today that 20% of the people who’ve installed their free Mac antivirus has malware. That’s not altogether surprising, but it’s also not nearly as big of a problem as it sounds.

One in 36 systems has Mac malware, which means the Mac has an infection that could actually be harming the system itself. That number is low but believable. In my experience, the people who seek out antivirus software are usually the ones who need it the least. You still don’t want those viruses lingering, and you want to know when they show up. If I get an infected Word document from a Windows machine, it may not just be that other guy’s problem.

The reason is that an infected file is no longer trustworthy. If I have an Excel spreadsheet containing this year’s budget and it’s infected, that raises the possibility that the virus mangled one or more figures in that budget. If I have someone’s resume and it’s infected, the resume might not be truthful anymore. So the receiver of these files should treat them with suspicion and immediately start asking questions. Respond back, and ask the owner to clean the file and verify the information in it.

And if the receiver doesn’t have a good antivirus program with real-time scanning turned on, he or she may act on the information on those files before realizing they are potentially compromised. He or she may also pass them on to someone else who can be infected.

That 1 in 36 figure is likely to grow. A new version of Flashblock has just surfaced. And looking back a decade, success breeds copycats. At this point I’m more concerned about Flashblock’s copycats than I am about Flashblock.

Everyone I know who was around 10 years ago had an experience with a virus outbreak in a workplace. The outbreak was unpleasant at the time, but ultimately it led to better security practices. It got rid of the it-can’t-happen-to-me attitude.